The disclosure relates to aisle width sensor for a mobile storage system for determining the width between adjacent movable storage units, particularly when creating an aisle therebetween. The sensor includes a first bracket which is slidable with respect to a second bracket. The first and second brackets are attached to respective first and second arms of a scissor arm arrangement between the adjacent storage units. The sensor provides an output, particularly an analog output, which is proportional to the distance between the adjacent storage units and therefore simple to calculate and process for the central controller of the mobile storage system.
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1. A mobile storage system, comprising:
at least one movable storage unit;
an opposing object selected from the group consisting of a wall, a second mobile storage unit, and a stationary storage unit;
an electronic control system determining the location of said at least one movable storage unit and generating signals to move said at least one movable storage unit;
sensor assemblies between successive movable storage units or opposing objects, comprising:
a first arm with a first end and a second end;
a second arm with a first end and a second end, wherein said first end of said first arm is pivotably arranged with respect to said first end of said second arm, said second end of said first arm being arranged to attach to the first movable storage unit and said second end of said second arm being arranged to attach to the second movable storage unit;
a first bracket secured to said first arm;
a second bracket secured to said second arm and slidably engaged with said first bracket;
a sensor within said first bracket sensing relative movement of said second bracket and generating a signal in response thereto and communicating the signal to said electronic control system.
2. The mobile storage system of
3. The mobile storage system of
4. The mobile storage system of
5. The mobile storage system of
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1. Field of the Invention
The present invention relates to a sensor which senses the width of an aisle created in a mobile storage system when movable storage units are moved to open or close the aisles. The sensor provides a signal to the storage system controller to allow it to determine when to accelerate, decelerate, start and stop moving storage units when creating aisles for user access.
2. Description of the Prior Art
Mobile storage systems are well known in the prior art. These systems include a plurality of storage units, typically bookcases, wherein the end storage units are stationary and the intermediate units are mounted on rails and include an electric motor or other prime mover to propel the storage units along the rails. Typically, the storage units are arranged so that there is sufficient room for a single access aisle within the storage system and the mobile storage units are moved in order to select between which of the storage units the single access aisle is formed.
This general configuration is disclosed in U.S. Pat. No. 5,359,191 to Griesemer et al. entitled “Cross-Aisle Photo-Detector for Mobile Storage System Having a Light Detector Mounted to the Movable Storage Unit”.
It has been recognized in the prior art, such as in the above Griesemer et al. reference, that these mobile storage units can be very heavy, particular when full of books or other inventory, and that safety systems are required to prevent the closure of an access aisle between two storage units.
In order to control these units, limit switches have been used, such as disclosed in U.S. Pat. Nos. 5,005,923 and 5,044,703, both entitled “Limit Switch Apparatus Assembly for Mobile Storage Units” and issued to Dahnert. However, these references disclose apparatus which works only when an aisle is closing and cannot be used to decelerate or stop an opening aisle.
Similar deficiencies are encountered in the use physical limits switches on the lower carriage of a storage unit or on the overhead scissor arms and in the use of optical distance sensors. Moreover, optical distance sensors have minimum and maximum sensing limitation that must be accommodated when implementing the sensor. These sensors further typically have a non-linear response which must be compensated for in the controller and are subject to external influences such as ambient lighting and target variations. These sensors are also not suitable for sensing the limits of an opening aisle and do not provide hard-wired “end-of-travel” limits.
U.S. Pat. No. 5,670,778 entitled “Presence Detector for Mobile Storage Systems” issued on Sep. 23, 1997 to Smith (the inventor of the present application) discloses a safety system using an array of infrared light sources to detect the presence of a person or object within the aisle created by separated storage units.
Further improvements are sought wherein an electronic processor can monitor the distance between all storage units within the mobile storage system. Moreover, the use of a sensor with a linear output (that is, a signal directly proportional to the distance between adjacent storage units) is desired in order to simplify the required signal processing.
It is therefore an object of the present invention to provide an apparatus and method for monitoring the distance between successive storage units within a mobile storage system.
It is therefore a further object of the present invention to provide an apparatus and method for accomplishing the above objects within a very simple framework, particularly that the signal related to the distance between the successive storage units is linear, or directly proportional to such distance.
These and other objects are attained by providing an aisle width sensor which senses the width of an aisle created in a mobile storage system when movable storage units are moved to open or close the aisles. More specifically, the aisle width sensor is mounted near the pivot point of scissor arm assembly, such as is commonly used to carry power and control signals between movable storage units, that is suspended in the aisle between two movable storage units. The sensor assembly includes two brackets that are fastened together but can slide in slots thereby allowing the brackets to move toward each other or away from each other. A linear sensor is mounted on one of the brackets while the other bracket is connected to the sensor actuator arm. As a result, when the sensor brackets are pulled apart or pushed together, the sensor actuator arm is moved from one end to the other. The sensor movement results in an analog signal. The linear sensor is typically mounted on a printed circuit board that provides a mounting method and wiring connections, and further allows a cable to be connected to a simple connector. Additionally, limit switches may be optionally included to provide electrical end-of-travel limits when used in multiple aisle applications.
As a result, the sensor measures the difference between two existing scissor arms that are connected to each side of the movable storage units to provide an accurate measurement of the aisle width. Measuring the distance between the arms, rather than the angle or position of one of the arms) eliminates the position sensing variations caused by changes in loading and other physical variations. This is especially important when the aisle is nearly closed and the angular position of the arms can vary greatly.
As the sensor operates over the full range of an aisle width, this sensor may be used to limit the size of opening aisles and therefore allows a system to control multiple open aisles. Multiple open aisle systems have additional aisle space allocated that is intended to allow more than one aisle to be opened at a time. The width of any single aisle to be opened must therefore be sensed to create standard aisle widths and limited, preferably with hard-wired end-of-travel switches, to prevent overextending the scissor arms and causing damage to the system. Additionally, other limits can be provided easily and various gaps between ranges can be used for fire related ventilation, sprinkler access, space for filing of protruding items, etc. Virtually all aisle widths can be set by programming references that are compared with the signal from the variable aisle width sensor.
The sensor produces an analog signal that is linear and directly proportional to the width of an aisle thereby providing an unlimited number of aisle width limit sensing positions. The linear analog output signal allows all limit positions to be electrically determined and therefore can be easily adjusted or programmed rather than mechanically or physically adjusted. Because of the linear response, slowdown limits can be automatically predetermined by calculating a fixed reference offset from any programmable limit position. The deceleration limit typically activates prior to the final limit to slow down the movement of the storage unit before stopping.
The resulting analog sensing method is a low cost method to provide an unlimited number of limit sensing positions. A three-wire cable is required to sense any number of limit positions. Moreover, the analog sensing element itself is also very low cost. Additionally, the sensor provides a simple method to implement hard-wired “end-of-travel” limit switch functions that are desirable to further limit and prevent overextending of scissor arms when used in a multiple aisle system mode of operation.
The analog sensor element can be optionally replaced with simple limit switches when only simple aisle closing functions are needed and electrical adjustability is not required.
Further objects and advantages of the invention will become apparent from the following description and claims, and from the accompanying drawings, wherein:
Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that
Printed circuit board 50, which includes the linear sensor, is mounted on the interior of wall 20 (shown in cut-away on
As shown in
The resulting analog signal from printed circuit board 50 is sent to a storage system controller 200 (see
Thus the several aforementioned objects and advantages are most effectively attained. Although a single preferred embodiment of the invention has been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.
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| 5495677, | Oct 01 1993 | STRIDE TOOL, INC | Digital display micrometer gauge |
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| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| May 19 2005 | SMITH, JAK L | KARDEX SYSTEMS INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 016647 | /0118 | |
| May 27 2005 | Kardex Systems Inc. | (assignment on the face of the patent) | / |
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